If Ebsta appears un-installed everyday, it's likely that the area of the user's profile where extensions and their settings are stored are not being persisted.
When Chrome and Ebsta are installed by an IT department, or IT service provider, Chrome can be configured to use a different directory that will resolve the problem.
Chrome extensions, such as Ebsta, and their settings are, by default, stored in the %localappdata% directory of the user's profile.
Often when roaming profiles are used (as with Terminal Server and Citrix), only the %appdata% (roaming) profiles are persisted.
This means that every day, or following log off/login, the extensions and their settings will have disappeared and will require installing.
What's the Solution?
The resolution is to configure Chrome to use a different, persisted directory for storing user data. This can be done via Group Policy. You can refer to more information on this here:
http://dev.chromium.org/administrators/policy-list-3#UserDataDir
Once this is done, the users can either re-install Ebsta themselves, or Ebsta can be installed for all users via Group Policy. You can refer to more information on this here:
http://dev.chromium.org/administrators/policy-list-3#ExtensionInstallForcelist